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Recent items
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Telomerase inhibition - unfulfilled hopes in the perfect molecular target
- Natalia Maciejewska
Telomerase plays a pivotal role in cell proliferation, homeostasis, and neoplastic transformation, making it a promising molecular target for cancer chemotherapy. Of note, although hTERT has been explored thoroughly as a target, none of the promising molecules has been approved as a drug until now. The subject of research conducted as part of my doctoral dissertation is explaining the cellular and molecular mechanism of action of new heterocyclic compounds derived from the class of carbazole, pyrazole, and anthraquinone. Of all the candidates tested, only anthraquinones inhibited telomerase activity. I have shown that the most active compound (TXT4), apart from the typical features of telomerase targeting molecules, also preferentially damages DNA on telomeres. Furthermore, I have found that TXT4 has an additional mechanism of action, consisting of multidirectional inhibition of tyrosine kinases. From among carbazoles, I selected compounds 5aa and 8, which primary mechanism of action is reactive oxygen species production. In addition, I showed that the most promising compound from the pyrazole class is PCH-1, whose anticancer activity is based on the stabilization of tubulin polymerization - the cytoskeleton-forming protein. On the basis of the conducted research, I determined the main mechanisms of action of new anti-cancer compounds, which in the future may employ as the basis for the design and synthesis of new potential pharmaceutical agents.
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Temperature Evolution, Material Flow, and Resulting Mechanical Properties as a Function of Tool Geometry during Friction Stir Welding of AA6082
- Aleksandra Laska
- Behzad Sadeghi
- Behzad Sadeghian
- Aboozar Taherizadeh
- Marek Szkodo
- Pasquale Cavaliere
The friction stir welding process was simulated for joining AA6082 aluminum alloy with the use of the computational fluid dynamics method. Two different tool geometries were used—a tapered cylindrical pin (simple pin) and a hexagonal pin with grooves (complex pin). The analysis of the simulations performed was discussed in terms of temperature evolution during the process, total heat input, residual stresses and material flow. Simulations revealed that a 5% higher temperature, equal to maximum 406 °C, was provided when using the complex pin than with the simple pin. Higher temperature and higher shear stresses during the welding with the complex pin caused the introduction of higher residual stresses in the weld. Experimental results on the produced welds allowed observation of the microstructure of the joints, hardness tests in cross sections and tensile strength tests. Due to the higher temperature during the process with the complex pin and the more efficient recrystallization process, grain refinement in the SZ was more pronounced. The average grain size in the stir zone for the weld produced with the complex pin was equal to 11 ± 1 µm, and in the case of the simple pin 14 ± 1 µm. The presented hardness profiles revealed that the weld produced with a complex pin had higher hardness in the stir zone, equal to 89.5 ± 1.3 HV, which is consistent with the Hall-Petch relationship. The obtained UTS values corresponded to the joint efficiency of 72.5 ± 4.9% and 55.8 ± 8.6% for the weld produced with the complex pin and the simple pin.
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Tensile and flexural moduli for human orbital wall bones – comparative study
- Paweł Lemski
- Krzysztof Żerdzicki
- Paweł Kłosowski
- Andrzej Skorek
- Marcin Zmuda Trzebiatowski
The main aims of the current research were: (1) to analyze in detail the tensile modulus and ultimate tensile strength (UTS) of orbital wall bones separately for the left and right orbit of the same cadaver and (2) to compare the obtained results with a flexural modulus of the left and right orbit reported earlier by A. C. van Leeuwen et al. [14]. A set of 54 specimens of orbital superior and/or medial walls harvested from 16 human skulls (4 female, 12 male) were tensioned at 0.01 mm/s till fracture. The samples were taken always from both orbits of the same cadaver. For each sample, cross-section area, apparent density, tensile modulus, and UTS were identified. For pooled female and male group apparent density for right and left orbit was identified to be 1.59 (± 0.52 SD) g/cm3 and 1.51 (±0.48 SD) g/cm3, tensile modulus of 2028 (±1729 SD) MPa and of 2706 (±2812 SD) MPa, and UTS of 14.17 (±15.00 SD) MPa and of 15.03 (±11.44 SD) MPa, respectively. For tensile tests, there were no statistical differences between the left and right orbit for pooled male and female groups for (a) apparent density (Student’s t-test p = 0.567), (b) UTS (Mann–Whitney U-test p = 0.350) and (c) tensile modulus (Mann–Whitney U-test p = 0.716). For bending tests, there were no statistical differences between the left and right orbit for the pooled male and female group for (a) orbital wall thickness (Student’s t-test p = 0.811) and (b) flexural modulus (Mann–Whitney U-test p = 0.206). The comparative analysis between tensile and flexural moduli for pooled left and right groups (with no distinction for male and female) revealed no statistically significant difference (Mann–Whitney U-test p = 0.074). The maximum tensile modulus was 7279 MPa and 9913 MPa for the right and left orbit, respectively, and was similar to the maximum flexural modulus of 6870 MPa and 9170 MPa reported in an earlier study, for the right and left orbit, respectively.
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Teoretyczno-doświadczalne modelowanie konwekcji wymuszonej nanocieczy
- Przemysław Kozak
Przedłożona rozprawa doktorska dotyczy badań eksperymentalnych oraz numerycznych konwekcji wymuszonej nanocieczy. Badane nanociecze wytworzone były z cieczy bazowych takich jak woda demineralizowana i mieszaniny wody z glikolem etylenowym w trzech proporcjach objętościowych 90:10, 80:20 i 60:40. Jako nanocząstki użyto Al2O3, a wytworzone nanociecze miały koncentracje masowe 0,1%, 1% i 5%. Wyznaczono eksperymentalnie dynamiczny współczynnik lepkości oraz współczynnik przewodzenia ciepła badanych nanocieczy. Wyznaczono współczynnik intensyfikacji cieplno-hydraulicznej badanych nanocieczy. Wyniki eksperymentalne porównano z wynikami obliczeń numerycznych.
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Terminal charging scheduling of battery electric buses based on vehicle routing problem
- Bálint Csonka
- Mikołaj Bartłomiejczyk
Electric buses are considered to be a viable solution for reducing emission in dense urban areas. However, the greater charging time is a huge challenge for operators. In this paper, charging scheduling method was elaborated based on vehicle routing problem using mixed-integer linear programming model. The main novelty of the paper is the combination of modelling aspect, namely flexible turn sequence and heterogeneous shared charging infrastructure. It was found that the method helps to reduce dwelling time and the number of buses in operation. In the future, we plan to integrate driver regulations, heterogeneous bus fleet, multiple depots and terminals into the model.
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Testing of Technical Fabrics under Fast Camera Control
- Paweł Kłosowski
- Krystyna Michałowska
- Marek Przyborski
- Wojciech Jurczak
The dynamic development of measurement and recording techniques has been changing the way one conceives material strength. In this study, two different methods of evaluating the strength of fabrics are compared. The first is the typical and commonly used technique based on the use of a testing machine. The second method uses the so-called “fast camera” to monitor the entire process of the destruction of a fabric sample and analyse the behav-iour of the fabric during the experiment. Both methods provide interesting data and present a very specific way of experimentally evaluating the strength of fabrics.
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Testing the Effect of Bathymetric Data Reduction on the Shape of the Digital Bottom Model
- Wiktor Mujta
- Marta Wlodarczyk-Sielicka
- Andrzej Stateczny
Depth data and the digital bottom model created from it are very important in the inland and coastal water zones studies and research. The paper undertakes the subject of bathymetric data processing using reduction methods and examines the impact of data reduction according to the resulting representations of the bottom surface in the form of numerical bottom models. Data reduction is an approach that is meant to reduce the size of the input dataset to make it easier and more efficient for analysis, transmission, storage and similar. For the purposes of this article, test datasets were created by discretizing a selected polynomial function. The real dataset, which was used to verify the analyzes, was acquired using an interferometric echosounder mounted on a HydroDron- 1 autonomous survey vessel. The data were collected in the ribbon of Lake Klodno, Zawory. Data reduction was conducted in two commercial programs. Three equal reduction parameters were adopted for each algorithm. The research part of the paper presents the results of the conducted analyzes of the reduced bathymetric datasets based on the visual comparison of numerical bottom models, isobaths, and statistical parameters. The article contains tabular results with statistics, as well as the spatial visualization of the studied fragments of numerical bottom models and isobaths. This research is being used in the course of work on an innovative project that aims to develop a prototype of a multi-dimensional and multi-temporal coastal zone monitoring system using autonomous, unmanned floating platforms at a single survey pass.
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Textile reinforced concrete members subjected to tension, bending, and in-plane loads: Experimental study and numerical analyses
- Adam Ścięgaj
- Sebastian Almfeldt
- Fredrik Larsson
- Karin Lundgren
Textile reinforced concrete has raised increasing research interest during the last years, mainly due to its potential to be used for freeform shell structures involving complex load situations. Yet, most experimental work has focused on test setups with primarily uniaxial loading. In the current work, such setups are complemented with a novel test setup of deep beams, including in-plane bending and shear. Further, nonlinear finite element analyses were carried out, applying an earlier calibrated bond-slip relation and efficiency factors for strength and stiffness of the textile reinforcement. It was found that the structural behaviour in terms of the overall stiffness, ultimate load and deformation, number of cracks, and total (summed) crack width, could be described with reasonably good accuracy. The inclusion of a calibrated efficiency factor for the stiffness of the yarn was shown to be vital. Moreover, it was shown to be important to weaken and randomise the material properties of the concrete at the location of transverse yarns, to trigger localisation (cracking) in the numerical model.
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Texture or Linker? Competitive Patterning of Receptor Assembly toward Ultra-Sensitive Impedimetric Detection of Viral Species at Gold-Nanotextured Titanium Surfaces
- Wiktoria Lipińska
- Adrian Olejnik
- Monika Janik
- Mateusz Brodowski
- Karolina Sapiega
- Mattia Pierpaoli
- Katarzyna Siuzdak
- Robert Bogdanowicz
- Jacek Ryl
In this work, we study the electrodes with a periodic matrix of gold particles pattered by titanium dimples and modified by 3-mercaptopropionic acid (MPA) followed by CD147 receptor grafting for specific impedimetric detection of SARS-CoV-2 viral spike proteins. The synergistic DFT and MM/MD modeling revealed that MPA adsorption geometries on the Au–Ti surface have preferential and stronger binding patterns through the carboxyl bond inducing an enhanced surface coverage with CD147. Control of bonding at the surface is essential for oriented receptor assembling and boosted sensitivity. The complex Au–Ti electrode texture along with optimized MPA concentration is a crucial parameter, enabling to reach the detection limit of ca. 3 ng mL–1. Scanning electrochemical microscopy imaging and quantum molecular modeling were performed to understand the electrochemical performance and specific assembly of MPA displaying a free stereo orientation and not disturbed by direct interactions with closely adjacent receptors. This significantly limits nonspecific interceptor reactions, strongly decreasing the detection of receptor-binding domain proteins by saturation of binding groups. This method has been demonstrated for detecting the SARS virus but can generally be applied to a variety of protein–antigen systems. Moreover, the raster of the pattern can be tuned using various anodizing processes at the titania surfaces.
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The accessibility, necessity, and significance of certified reference materials for total selenium content and its species to improve food laboratories' performance
- Chintankumar Padariya
- Małgorzata Rutkowska
- Piotr Konieczka
Micronutrients are one of the most important groups of nutrients that our body needs daily in trace amounts to tackle deficiencies. Selenium (Se) is a mineral that occurs naturally in foods and is an essential component of selenoproteins that support the healthy functioning of the human body. Therefore, monitoring dietary Se concentrations must be a higher priority to meet daily intakes. Fulfillment can be addressed through applying various analytical techniques, and the certified reference materials (CRMs) tool plays a crucial role in quality assurance/quality control (QA/QC). The availability of certified CRMs for total Se content with addition to their species is presented. The review emphasizes the necessity of incorporating more food matrix CRMs certifying Se species, apart from total Se content, to meet method validation requirements for food analysis laboratories. This would help CRM producers bridge the gap between available food matrix materials that are not certified for Se species.
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The Action Mechanisms, Anti-Cancer and Antibiotic-Modulation Potential of Vaccinium myrtillus L. Extract
- Mikayel Ginovyan
- Anush Babayan
- Anahit Shirvanyan
- Alvard Minasyan
- Barbara Kusznierewicz
- Izabela Koss-Mikołajczyk
- Anne Vejux
- Agnieszka Bartoszek-Pączkowska
- Naira Sahakyan
Herbal medicinal products containing Vaccinium myrtillus L. (bilberry) fruits and fruit extracts are widely available in the market. Although bilberry leaves and stems are considered as bio-waste, they contain much higher levels of phenolic compounds than fruits. The study aimed to investigate the antimicrobial and anticancer potential of aerial part extracts from Vaccinium myrtillus L. (V. myrtillus, VM) plants harvested at high altitudes in Armenian landscape and characterize the bioactive phytochemicals. For evaluation of antioxidant properties, chemical-based tests (total phenolic and flavonoid content, and antiradical activity in 2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) tests) and cellular antioxidant activity (CAA) assay were applied. Genotoxicity and anticancer properties of the extract alone and in combination with fluorouracil were explored in human cancer and normal cell lines. Antibacterial properties of V. myrtillus ex- tract alone and in combination with antibiotics, as well as their effect on proton-flux rate through cell membrane were explored on bacterial strains. The characterization of active phytochemicals was done using Liquid Chromatography-Quadrupole-Orbitrap High-Resolution Mass Spectrometry (LC-Q-Orbitrap HRMS).The V. myrtillus aerial part extract demonstrated promising antioxidant properties in all tests. The selective cytotoxic activity was documented against various cancer cell lines (human colon adenocarcinoma (HT29), human breast cancer (MCF- 7) and human cervical carcinoma (HeLa)), while it did not inhibit the growth of tested human normal primary renal mixed epithelial cells (HREC) even at 10-fold higher concentrations. The extract did not have genotoxic properties in comet assay making it a potential source for the development of anticancer preparations. The investigated extract did not directly inhibit the growth of Escherichia coli (E. coli) and Salmonella typhimurium (S. typhimurium) strains at up to 1 mg/mL concentration. However, V. myrtillus extract enhanced the kanamycin intake and increased its efficiency against E. coli strain. The phytochemical characterization of the extract showed the presence of different groups of phenolics. Based on obtained data, we suggest the aerial parts of the V. myrtillus plant as an alternative source of bioactive natural products for food supplements, nutraceuticals, functional foods and medicine.
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The Application of Cluster Analysis in the Assessment of the Weldability of Unalloyed Steels
- Anna Szewczyk
- Klaudia Górska
- Adrian Wolski
- Dariusz Fydrych
Non-alloy steels constitute a large group of steels characterised by diversified chemical composition, structural morphology and a wide range of mechanical properties (determining weldability). The paper presents results of multidimensional analyses (based on cluster analysis) of 110 selected unalloyed steel grades. Properties adopted as diagnostic features included the chemical composition, mechanical properties (yield point) and values of selected indicators concerning susceptibility to technological crack formation. The analyses (performed using Ward’s and k-means methods) resulted in a division of the 110 steels into five steel groups (clusters). The comparison of results obtained using two clustering methods and involving various classification criteria revealed that multidimensional analyses constituted a prospective method making it possible to assess the weldability of steels. However, results of such multidimensional analyses should be subjected to thorough and substantive analyses.
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The Application of Dynamic Electrochemical Impedance Spectroscopy (DEIS) Technique in Corrosion and Corrosion Inhibition Studies
- Paweł Ślepski
- Husnu Gerengi
- Moses Solomon
- Saviour Umoren
orrosion studies have attracted considerable interest in the areas of materials chemistry and industrial chemistry, as it affects the direct and indirect costs of industry, leading to huge economic setbacks due to the need for repair, maintenance, and even shutdowns due corrosion damage. This new volume is a comprehensive resource that presents new and up-to-date, theoretical, and experimental corrosion inhibition studies.
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The Arnold conjecture in $ \mathbb C\mathbb P^n $ and the Conley index
- Luca Asselle
- Marek Izydorek
- Maciej Starostka
n this paper we give an alternative, purely Conley index based proof of the Arnold conjecture in CP^n asserting that a Hamiltonian diffeomorphism of CP^n endowed with the Fubini-Study metric has at least (n+1) fixed points.
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The assessment of solar photovoltaic in Poland: the photovoltaics potential, perspectives and development
- Bartłomiej Igliński
- Grzegorz Piechota
- Urszula Kiełkowska
- Wojciech Kujawski
- Michał Bernard Pietrzak
- Mateusz Skrzatek
The following article explains the current condition of the photovoltaics sector both in Poland and worldwide. Recently, a rapid development of solar energy has been observed in Poland and is estimated that the country now has about 700,000 photovoltaics prosumers. In October 2021, the total photovoltaics power in Poland amounted to nearly 5.7 GW. The calculated technical potential of photovoltaics in Poland is 153.484 PJ (42.634 TWh). This would cover 26.04% of Poland’s electricity needs. The main aim of the article is to assess the level of development of the photovoltaic market in Poland, the genesis of its creation, description of the current situation and determination of the development opportunities. As part of the aim, programs supporting the development of solar energy in Poland have been described and the SWOT analysis has also been performed. The strengths of photovoltaics include high social acceptance and low costs of photovoltaics system operation, while opportunities include rapidly increasing technological efficiency and decreasing cost of solar systems. On the other hand, weaknesses include the high costs of photovoltaics systems and the disparities in the amount of solar energy reaching the market during the year, whereas climate change and the coronavirus pandemic are threats. In 2020, PV became an investment hit in the energy sector and an economic driver in Poland. In the difficult time of two lockdowns caused by the global pandemic, domestic PV made a significant contribution to the maintenance of investment processes in the amount of PLN 9.5 billion and provided Poland with 35 thousand jobs. In 2020, 1.5% of the country’s electricity came from PV sources. In 2021, it will be 3.5%, and by 2025, solar energy will provide approx. 10% of Poland’s electricity. It is worth examining the development of photovoltaics from a broad and long-term perspective. The spectacular development of photovoltaics in Poland is due to hitting the right time window and reducing technology costs, but most of all, it is based on the cooperation of stakeholders and trust in the regulatory environment.
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The Challenge of Quantification: An Interdisciplinary Reading
- Marta Kuc-Czarnecka
- Monica Di Fiore
- Samuele Lo Piano
- Arnald Puy,
- Andrea Saltelli,
The present work looks at what we call “the multiverse of quantification”, where visible and invisible numbers permeate all aspects and venues of life. We review the contributions of different authors who focus on the roles of quantification in society, with the aim of capturing different and sometimes separate voices. Several scholars, including economists, jurists, philosophers, sociologists, communication and data scientists, express concerns or identify critical areas of our relationship with new technologies of ‘numericization’. While mindful of the important specificities of the different families of quantification, we use our broad and holis- tic canvas to explore possible spaces for a more systematic investigation of incumbent and novel quantifications, as to increase communication among disciplinary communities, and among these and society, in the pursuit a democratic agency and self-defence.
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The characterization of collagen‑based scaffolds modified with phenolic acids for tissue engineering application
- Beata Kaczmarek-Szczepańska
- Izabela Polkowska
- Marcin Małek
- Janusz Kluczyński
- Katarzyna Paździor-Czapula
- Marcin Wekwejt
- Michno Anna
- Anna Ronowska
- Anna Pałubicka
- Beata Nowicka
- Iwona Otrocka-Domagała
The aim of the experiment was to study the morphology of collagen-based scaffolds modified by caffeic acid, ferulic acid, and gallic acid, their swelling, and degradation rate, as well as the biological properties of scaffolds, such as antioxidant activity, hemo- and cytocompatibility, histological observation, and antibacterial properties. Scaffolds based on collagen with phenolic acid showed higher swelling rate and enzymatic stability compared to scaffolds based on pure collagen, and the radical scavenging activity was in the range 85–91%. All scaffolds were non-hemolytic and compatible with surrounding tissues. Collagen modified by ferulic acid showed potentially negative effects on hFOB cells as a significantly increased LDH release was found, but all of the studied materials had antimicrobial activity against Staphylococcus aureus and Escherichia coli. It may be assumed that phenolic acids, such as caffeic, ferulic, and gallic acid, are modifiers and provide novel biological properties of collagen-based scaffolds. This paper provides the summarization and comparison of the biological properties of scaffolds based on collagen modified with three different phenolic acids.
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The coexistence and competition of canonical and comammox nitrite oxidizing bacteria in a nitrifying activated sludge system – Experimental observations and simulation studies
- Jacek Mąkinia
- Mohamad-Javad Mehrani
- Przemysław Kowal
- Dominika Sobotka
- Martyna Godzieba
- Sławomir Ciesielski
- Jianhua Guo
The second step of nitrification can be mediated by nitrite oxidizing bacteria (NOB), i.e. Nitrospira and Nitrobacter, with different characteristics in terms of the r/K theory. In this study, an activated sludge model was developed to account for competition between two groups of canonical NOB and comammox bacteria. Heterotrophic denitrification on soluble microbial products was also incorporated into the model. Four 5-week washout trials were carried out at dissolved oxygen-limited conditions for different temperatures (12℃ vs. 20℃) and main substrates (NH4+-N vs. NO2--N). Due to the aggressive reduction of solids retention time (from 4 to 1 d), the biomass concentrations were continuously decreased and stabilized after two weeks at a level below 400 mg/L. The collected experimental data (N species, biomass concentrations, and microbiological analyses) were used for model calibration and validation. In addition to the standard predictions (N species and biomass), the newly developed model also accurately predicted two microbiological indicators, including the relative abundance of comammox bacteria as well as nitrifiers to heterotrophs ratio. Sankey diagrams revealed that the relative contributions of specific microbial groups to N conversion pathways were significantly shifted during the trial. The contribution of comammox did not exceed 5% in the experiments with both NH4+-N and NO2--N substrates. This study contributes to a better understanding of the novel autotrophic N removal processes (e.g. deammonification) with nitrite as a central intermediate product.
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The comparison of antioxidant properties and nutrigenomic redox-related activities of vitamin C, C-vitamers, and other common ascorbic acid derivatives
- Patrycja Jakubek
- Klaudia Suliborska
- Monika Kuczyńska
- Muhammad Asaduzzamana
- Karol Parchem
- Izabela Koss-Mikołajczyk
- Barbara Kusznierewicz
- Wojciech Chrzanowski
- Jacek Namieśnik
- Agnieszka Bartoszek-Pączkowska
The term ‘vitamin C’ describes a group of compounds with antiscorbutic activity of L-ascorbic acid (AA). Despite AA’s omnipresence in plant-derived foods, its derivatives have also been successfully implemented in the food industry as antioxidants, including the D-isomers, which lack vitamin C activity. This study aimed to determine the relationship between redox-related activities for five derivatives of AA using electrochemical, chemical, and biological approaches. Here we report that AA, C-vitamers, and other commonly consumed AA derivatives differ in their redox-related activities. As long as the physiological range of concentrations was maintained, there was no simple relationship between their redox properties and biological activity. Clear distinctions in antioxidant activity were observed mostly at high concentrations, which were strongly correlated with electrochemical and kinetic parameters describing redox-related properties of the studied compounds. Despite obvious similarities in chemical structures and antioxidant activity, we showed that C-vitamers may exhibit different nutrigenomic effects. Together, our findings provide a deeper insight into so far underinvestigated area combining chemical properties with biological activities of commonly applied AA derivatives.
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The complexity of bicriteria tree-depth
- Piotr Borowiecki
- Dariusz Dereniowski
- Dorota Osula
The tree-depth problem can be seen as finding an elimination tree of minimum height for a given input graph G. We introduce a bicriteria generalization in which additionally the width of the elimination tree needs to be bounded by some input integer b. We are interested in the case when G is the line graph of a tree, proving that the problem is NP-hard and obtaining a polynomial-time additive 2b-approximation algorithm. This particular class of graphs received significant attention in the past, mainly due to a number of potential applications, e.g.in parallel assembly of modular products, or parallel query processing in relational databases, as well as purely combinatorial applications including searching in tree-like partial orders (which in turn generalizes binary search on sorted data).
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The congruence of mental models in entrepreneurial teams – implications for performance and satisfaction in teams operating in an emerging economy
- Paweł Ziemiański
- Katarzyna Stankiewicz
- Michał Tomczak
- Beata Krawczyk-Bryłka
Purpose – The paper aims to explore the relationship between the congruence of mental models held by the members of entrepreneurial teams operating in an emerging economy (Poland) and entrepreneurial outcomes (performance and satisfaction). Design/methodology/approach – The data obtained from 18 nascent and 20 established entrepreneurial teams was analysed to answer hypotheses. The research was quantitative and was conducted using an online questionnaire. Data was collected from each of the teams at two stages. Members of entrepreneurial teams were surveyed independently, which allowedmeasuring the congruence of their mental models pertaining to running a venture. Findings – Findings reveal that team members’ mental model congruence is significantly related to financial performance and members’ satisfaction in the case of established entrepreneurial teams. However, in the case of nascent teams, there is no relationship between analysed variables. Practical implications – Implications for theory and practice are offered with a special emphasis on entrepreneurship education. The concept of team mental model congruence is proposed to be included in training of nascent entrepreneurial teams, experienced companies and students. Originality/value – The concept of team mental models investigated by the authors has been underexplored in entrepreneurship research. Results indicate that at least in some entrepreneurial teams, team mental models’ congruence is related to obtained outcomes. The paper proposes that principles of effectuation and causation can serve as the lens through which the mental model pertaining to running a venture can be analysed. It allows expanding studies on the congruence of team mental models in entrepreneurial teams beyond the strategic consensus.
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The correlation between nutritional and health potential and antioxidant properties of raw edible oils from cultivated and wild plants
- Dorota Martysiak-Żurowska
- Małgorzata Orzołek
The nutritional properties and health potential of oils from 15 various cultivated and wild plants were investigated on the basis of the fatty acids profiles, total carotenoids and tocopherols content, antioxidant properties and health potential indexes such as atherogenicity index (AI). The oil contents of the plants varied between 0.9 g/100 g for lychee seeds and 29.7 g/100 g for borage seeds. The tocopherol content in oils ranged from 0.31 (lingonberry fruits) to 226.23 mg/100 g (hawthorn pulp), carotenoids ranged from 0.36 (borage seeds) to 14.22 mg/100 g (blackcurrant seeds). In four oils (raspberry seed, strawberry seed, lingonberry fruits, blackcurrant seeds) the PUFA contents contributed over 70% of the total fatty acids (FA), which was associated with the best values health potential indexes. It was found that TAC (Total Antioxidant Capacity) can be an indirect measure of the levels of carotenoids and tocopherols in oils. Additionally, a positive correlation between the level of carotenoids and the FA n-3 was demonstrated. Determining such relationships may facilitate research into new sources of valuable edible oils useful for the production of functional foods, dietary supplements and cosmetics.
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The correlation of fractal dimension to fracture surface slope for fatigue crack initiation analysis under bending-torsion loading in high-strength steels
- Wojciech Macek
- Ricardo Branco
- Przemysław Podulka
- Reza Masoudi Nejad
- José Domingos Costa
- J. A. M. Ferreira
- C. Capela
In this study, the fractal dimension of fatigue fracture surfaces is investigated in order to find an alternative failure loading indicator. Some of many metrological factors are generalized by reducing the fracture surface structure to one factor and develop an entire fracture surface procedure by analyzing the impact of surface slope and calculation resolution. Three notched geometries are studied under cyclic bending-torsion: 34CrNiMo6 high-strength steel bars with transverse blind holes; (ii) 34CrNiMo6 high-strength steel bars with lateral U-shaped notches; and (iii) 18Ni300 maraging steel hollow bars with transverse holes produced by selective laser melting. The surface topographies of fatigue fractures were measured with an optical profilometer. The bending-torsion ratio, maximum local von Mises equivalent stress and the number of cycles to crack initiation are examined using the fractal dimension. Moreover, a comparison was also made for conventional surface topography parameters such as root mean square height and void volume. A fatigue crack initiation model based on surface topography and loading conditions is proposed. The model relies on the product of the maximum local von Mises equivalent stress and the fractal dimension divided by the root mean square height to void volume ratio. The results show that the fracture plane geometry, expressed by the fractal dimension Df, can facilitate the estimation of post-failure loading history. In particular, the analysis based on the enclosing boxes method (EBM) is more accurate when it is used as an extra-fine resolution without any plane leveling.
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The Cultures of Knowledge Organizations: Knowledge, Learning, Collaboration (KLC)
- Wioleta Kucharska
- Denise A. D. Bedford
This book focuses on seeing, understanding, and learning to shape an organization’s essential cultures. The book is grounded on a fundamental assumption that every organization has a de facto culture. These “de facto cultures” appear at first glance to be serendipitous, vague, invisible, and unmanaged. An invisible and unrecognized de facto culture can undermine business goals and strategies and lead to business failures. The authors believe that humans can learn to “see” culture around them and understand their influence on individuals, teams, organizations, and societies. At its core, the book lays out the levels of culture to help the reader “see” and learn how to shape a knowledge organization’s cultures. Learning to see and understand the culture, mainly organizational culture, is critical in today’s hyperdynamic knowledge economy. Culture will always dominate strategy in any economy. However, it can play an even more significant role in the knowledge economy, where knowledge is the primary form of capital and the most critical production factor. To thrive and survive in the knowledge economy, managers must “see” their company culture’s power to shape the company’s course and learn to gain and sustain knowledge, learning, and collaboration (KLC) cultures synergy. Hyperdynamic business reality requires smart actions. When managers “see” their cultures as an asset, they have an opportunity to shape those cultures and use them for the company’s best.
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The dependence of linear viscoelasticity limits of cold-recycled mixtures on time of curing and compaction method
- Mariusz Jaczewski
- Cezary Szydłowski
- Bohdan Dołżycki
Cold-recycled mixtures are currently among the most widely used and investigated methods that enable recycling of old pavement structures in an environmentally friendly manner. Upon milling, the old pavement structure – whose gradation can be improved with addition of virgin aggregate – is mixed and compacted at ambient temperature. The main binding agents are bituminous emulsion and cement. Due to their dual binding behaviour, cold-recycled mixtures present various problems and challenges in terms of correct testing. One of such challenges is the testing of stiffness modulus of cold-recycled mixtures. Apart from dependence of modulus on test temperature and time of curing, recent research proved its highly nonlinear behaviour, much wider than that of classical asphalt mixtures. The paper presents the results of research of linear viscoelasticity limits based on testing conducted in Simple Performance Tester (SPT) device for one cold-recycled mixture recipe, using samples prepared and compacted in different manner. One mixture was prepared in laboratory conditions from materials obtained from the field section. Second mixture was prepared on the basis of field-mixed materials (material prepared and mixed in field, compacted in laboratory). Additionally, cores obtained from the field at 28 and 180 days after compaction were tested. All mixtures were tested at the temperature of 20 C. Tests were performed 7, 14, 28, 42, 90 and 180 days after compaction. The controlled strain mode was chosen, with strain ranging from 20 to 200 lstrain. Stiffness modulus and phase angle were measured. The test showed that the linear viscoelasticity limits for stiffness modulus testing changed with the time that had elapsed since the compaction for all specimens – the initially low values (of 45–55 lstrain) increased with time and reached constant values (of 75–95 lstrain), with different levels depending on the specimen preparation method.
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The Design of Cavity Resonators and Microwave Filters Applying Shape Deformation Techniques
- Michał Baranowski
- Łukasz Balewski
- Adam Lamęcki
- Michał Mrozowski
- Jaione Galdeano
This article introduces shape deformation as a new approach to the computer-aided design (CAD) of high-frequency components. We show that geometry deformation opens up new design possibilities and offers additional degrees of freedom in the 3-D modeling of microwave structures. Such design flexibility is highly desirable if the full potential of additive manufacturing (AM) is to be exploited in the fabrication of RF and microwave devices. The use of deformation techniques in the design of high-frequency components allows the attainment of improved electrical parameters, such as high-quality factors for cavity resonators and wide higher-order mode separation. In this work, shape deformation with radial basis functions (RBFs) is integrated with an electromagnetic field simulator based on the 3-D finite-element method (FEM), allowing the semiautomated optimization of microwave components, such as cavity resonators and filters. The proposed strategy is used for the design of high Q-factor cavity resonators, cavity bandpass filters with improved spurious mode separation, and a compact twisted waveguide filter. Three designs of waveguide cavity filters with complex geometry are experimentally verified using 3-D-printed prototypes fabricated with selective laser melting (SLM) technology
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The Double Cognitive Bias of Mistakes: A Measurement Method
- Wioleta Kucharska
- Denise A. D. Bedford
- Aleksandra Kopytko
There is no learning without mistakes. However, making mistakes among knowledge workers is s�ll seeing shameful. There is a clash between posi�ve a�tudes and beliefs regarding the power of gaining new (tacit) knowledge by ac�ng in new contexts and nega�ve a�tudes and beliefs toward accompanying mistakes that are sources of learning. These contradictory a�tudes create a bias that is doubled by the other shared solid belief that “BOSSES NEVER MAKE MISTAKES.” The double cogni�ve bias of mistakes introduced by Kucharska and Bedford (2023) is assumed in this paper to harm organiza�onal learning and collec�ve intelligence development. To jus�fy this point empirically in this paper, the authors propose a procedure enabling the measurement of the double cogni�ve bias of mistakes. Moreover, to validate the proposed method, authors empirically examine the influence of the KLC cultures’ synergy on knowledge sharing and organiza�onal intelligence and compare obtained results with the effect observed for the sample free of the double bias of mistakes. Novelty: this studyis the first to propose iden�fying the double bias of mistakes and empirically exposing its impacts.
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The Effect of C45 Carbon Black-Phosphomolybdic Acid Nanocomposite on Hydrogenation and Corrosion Resistance of La2Ni9Co Hydrogen Storage Alloy
- Krystyna Giza
- Edyta Owczarek
- Andrzej Miszczyk
In this paper, we analysed the influence of corrosion processes and the addition of a carbon black-heteropoly phosphomolybdic acid (C45-MPA) nanocomposite on the operating parameters of a hydride electrode obtained on the basis of the intermetallic compound La2Ni9Co. The electrochemical properties of negative electrodes for NiMH batteries were studied using galvanostatic charge/discharge curves, the potentiostatic method, and electrochemical impedance spectroscopy (EIS). The morphology and chemical composition analysis of the studied electrodes were investigated by means of scanning electron microscopy (SEM) with supporting energy-dispersive X-ray analysis (EDS). For more structural information, FTIR analysis was performed. The results indicate that the presence of the C45-MPA nanocomposite in the electrode material increased both the discharge capacity of the hydride electrode and the exchange current density of the H2O/H2 system. The heteropoly acid-modified electrode is also more resistant to high discharge current densities due to its catalytic activity.
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The effect of hybridization of fire retarded epoxy/flax-cotton fiber laminates by expanded vermiculite: Structure-property relationship study
- Mateusz Barczewski
- Kamila Sałasińska
- Wojciech Raś
- Aleksander Hejna
- Sławomir Michałowski
- Paulina Kosmela
- Joanna Aniśko
- Anna Boczkowska
- Marek Szostak
The study describes the hybridization of epoxy/flax-cotton (EP/FF) composites containing ammonium polyphosphate (APP) with micrometric expanded vermiculite (VMT) (1–10 wt%). The efficiency of hybridization of flame retarded epoxy/flax-cotton composites was assessed by performing static tensile and flexural strength evaluation, supplemented by impact strength measurements of the composites. Moreover, thermal and thermomechanical analyses (DMA, DSC, and TGA) were performed. Epoxy composites were subjected to flammability using a PCFC microcalorimeter and cone calorimeter measurement to assess the burning behavior of composites. The introduction of the low-cost plate-shaped filler resulted in several favorable thermal effects while deteriorating the structure of the composite. The addition of small amounts of vermiculite (1–2 wt%) into the matrix modified with APP enabled the reduction of heat release rate (HRR) and total heat release (THR) by 60% and 20%, respectively. The comprehensive structure-properties analysis determined the critical filler contents, yielding synergistic flame-retardant effects with a limited negative impact on the composites' performance.
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The effect of impacted third molars on second molar external root resorption, a cross-sectional cone beam computed tomography study
- G. Gürses
- A. Akçakaya
- A. Aktı
- Olgun Aydin
Background: Third molars have the highest prevalence of impaction in teeth and can cause pathological damage on the adjacent second molars. This study aims to evaluate the effects of factors related to impacted third molars on external root resorption (ERR) in adjacent second molars using cone-beam computed tomography (CBCT). Material and Methods: In CBCTs, the effect of impacted third molars on the root surface of adjacent second molars was investigated. Inclusion criteria for subjects were being older than 16 and younger than 55, presence of at least one impacted third molar and adjacent second molar. Exclusion criteria were pathology, a follicle gap greater than 5 mm, crowned second molar, severe decay, an artifact on a radiologic image, and previous surgery on the second or third molars. The investigations were made based on age range, gender, tooth inclination, Pell-Gregory classification, retention type, contact area, root formation, pericoronal width, and tooth absence on the same quadrant for potential risk factors. The collected data were statistically analyzed with R software. The Chi-Square test was used to find out any significant difference. Logistic regression analyses were done for potential risk factors for ERR. Results: A total of 437 impacted third molars and adjacent second molars were investigated using CBCT. Of these, 381 met the inclusion criteria. Mesioangular and horizontal inclination, Pell-Gregory Class B-C, contact area, and retention type were found the statistically potential risk factors for ERR. Conclusions: The impacted third molar with horizontal or mesioangular position, and osseous retention, with Pell and Gregory Class B and C, are more likely to cause external root resorption in adjacent second molars
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The effect of multiaxial geocomposite reinforcement on fatigue performance and crack propagation delay in double-layered asphalt beams
- Piotr Jaskuła
- Dawid Ryś
- Cezary Szydłowski
- Michał Golos
- K. Kornacka
- Joanna Żółtko
- Jacek Kawalec
- Marcin Stienss
The presented study investigates the effect of a recently developed multiaxial geocomposite made of polypropylene geogrid and non-woven fabric on the delay of crack propagation, based on four-point bending tests of large asphalt concrete beams – both for reinforced and non-reinforced specimens. Several approaches are described in this study, including analysis of stiffness modulus decrease and analysis of crack propagation using dissipated energy. The study also includes investigation of the impact of reinforcement on shear resistance of the inter-layer bond. The reinforced system displays reduced decrease in stiffness during cyclic loading; it is able to bear loads over a longer period, in contrast to the unreinforced system. An increase in fatigue life by a factor of 10–22 is possible, as compared to the unreinforced system. The factor of relative increase in the number of cycles to the first initiation of crack in lower asphalt layer when reinforcement is introduced ranges from 5 to 10.
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The effect of PEDOT morphology on hexavalent chromium reduction over 2D TiO2/PEDOT photocatalyst under UV–vis light
- Agnieszka Sulowska
- Agnieszka Fiszka Borzyszkowska
- Karolina Cysewska
- Katarzyna Siwińska-Ciesielczyk
- Konstantin Nikiforow
- Grzegorz Trykowski
- Anna Zielińska-Jurek
The present study represents an approach to apply organic-inorganic hybrid materials for photocatalytic removal of heavy metals from the aqueous environment. The photocatalytic activity of the semiconductor modified with the conjugated polymer may depends on the conjugated polymer type, its amount and morphology. Therefore, in the present study the effect of poly (3, 4-ethylenedioxythiophene) (PEDOT) morphology on adsorption and photoreduction of Cr(VI) to Cr(III) under simulated solar light (UV–vis) and vis light (λ > 400 nm) was investigated. The composite of titanium (IV) oxide and PEDOT of different morphology was obtained using the waterin- oil microemulsion method. The obtained hybrid photocatalysts were characterized by diffuse reflectance spectroscopy (DR/UV–vis), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM, TEM), specific surface area (BET) and X-ray photoelectron spectroscopy (XPS) analyzes. PEDOT and its composites with TiO2 nanosheets of anatase were used for the degradation of highly toxic Cr(VI) under the simulated solar light. The 2D TiO2/PEDOT composite with PEDOT microvesicular morphology reveals the highest efficiency of Cr(VI) photoreduction to Cr(III). The synergistic
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The Effect of Sodium Tetrafluoroborate on the Properties of Conversion Coatings Formed on the AZ91D Magnesium Alloy by Plasma Electrolytic Oxidation
- Lukasz Florczak
- Ginter Nawrat
- Kazimierz Darowicki
- Jacek Ryl
- Jan Sieniawski
- Małgorzata Wierzbińska
- Krzysztof Raga
- Andrzej Sobkowiak
Magnesium and its alloys are widely used in many areas because of their light weight, excellent dimensional stability, and high strength-to-weight ratio. However, the material exhibits poor wear and corrosion resistance, which limits its use. Plasma electrolytic oxidation (PEO) is an effective surface modification method for producing ceramic oxide layers on Mg and their alloys. The influence of the additions of sodium tetrafluoroborate (NaBF4) and sodium fluoride (NaF) into alkaline-silicate electrolyte on the properties of the conversion layers formed in the magnesium AZ91D alloy has been investigated. Surface morphology and chemical composition were determined by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The anticorrosive properties of the layers were evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) methods in simulated body fluid (SBF). The presence of NaBF4 or NaF in the electrolyte increases the corrosion resistance of the protective layer. However, the best anticorrosive properties show the layers obtained in the presence of NaBF4. This is probably caused by the incorporation of boron and fluorine in the form of Mg (BF4)2 mainly in the barrier layer.
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The effect of sunscreen 4‐methylbenzylidene camphor in different and reproductive models, its bioaccumulation and molecular effects on ligand‐receptor interaction, and protein expression
- Cassandra Lax
- Elin Wicksell
- Anastasia Grip
- Jenni Viivi Linnea Niemi
- Wen Liu
- Alexandra Rafeletou
- Błażej Kudłak
- Helgi B. Schiöth
4-Methylbenzylidene camphor (4-MBC) is a photo-absorbing UV filter prevalently used in cosmetics, which can be absorbed into circulation and cause systemic effects. 4-MBC is continued to be released in the environment despite the growing knowledge about its bioaccumulation and endocrine disrupting effects. Previous reviews have mentioned UV-filter together but this review considers 4-MBC alone, due to its prevalence and concerning health effects. This review considers 4-MBC’s potential effects on human health regarding systemic and molecular effects, with the main focus on reproduction. Also, the potential bioaccumulation and interactions with receptor systems such as the oestrogen receptors β and α, and progesterone receptor are covered. Additionally, previous studies about 4-MBC’s effects on mRNA and protein expression, especially in the prostate and the brain are analysed. Furthermore, 4-MBC is reported to act with inflammatory pathways by activating p38 MAPK and NF-κB, leading to the production of inflammatory TNF-α and IL-6. 4-MBC was also found to induce apoptosis and inhibit cell proliferation and DNA repair. In conclusion, 4-MBC has wide-ranging effects in many different models interacting with multiple pathways causing long-term effects even at low doses and this knowledge can guide governmental risk assessment, regulation divisions and chemical industries.
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The effect of thermal modification on the quality of the milled surface of beech and pine wood
- Richard Kminiak
- Lukas Adamčík
- Daniel Chuchała
The article deals with the effect of thermal modification on the quality of the created surface during milling on CNC milling cutters. The quality of the created surface is evaluated based on surface roughness, specifically its roughness parameter Ra. The observed surface is created by a shank cutter with a diameter of 20 mm and three cutting edges in a spiral at a standard speed of 18,000. min-1. The article compares thermally modified pine wood and beech wood of at temperatures of 160, 180, 200 and 220°C with a reference sample of kiln dried wood of the given wood species. The article also monitors the variability of the quality of the created surface due to the change in the feed speed of 2, 4 and 6 m·min-1 and the thickness of removal of 1, 3 and 5 mm within the given degree of thermal modification. The article points to the fact that the average value of the arithmetic mean height (Ra) is below 10 μm for both types of wood, regardless of the degree of thermal modification. This meets the general requirements for the surface quality of furniture blanks. The mutual comparison of wood species showed that beech wood forms an average of 1.5 μm higher quality surface than wood pine. Thermal modification within both studied wood species improves the quality indicators of the created surface. In terms of the effect of specific temperatures, the highest quality of the created surface is at 180°C and deteriorates in the range of 180, 200, 160, 220°C. From the point of view of the influence of the investigated technological factors, no statistically significant influence of either the feed speed or the thickness of removed layer was demonstrated.
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The Effect of Titanium Oxyfluoride Morphology on Photocatalytic Activity of Fluorine-Doped Titanium(IV) Oxide
- Marta Kowalkińska
- Jakub Karczewski
- Anna Zielińska-Jurek
Titanium oxyfluoride (TiOF2) is a metastable product that can be obtained in a fluorine-rich environment. This material can also be a valuable precursor in the synthesis of titanium(IV) oxide (TiO2). However, the effect of TiOF2 morphology on the physicochemical properties of TiO2 has not been studied so far. In this work, single-phase TiOF2 was prepared by a solvothermal method. The as-synthesized samples exhibited a variety of morphologies, including different shapes and crystallite sizes. These materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDS), surface area measurements, thermal gravimetric analysis (TGA) and UV–vis diffuse reflectance spectroscopy (DR/UV–vis). Furthermore, TiOF2 samples were used as precursors in the synthesis of fluorine-doped titanium(IV) oxide and applied in photocatalytic phenol degradation under UV-vis light. The experiments showed that the crystallite size of the precursor, as well as the number of fluoride ions used in the synthesis, were the predominant factors that affected the photocatalytic activity of the final photocatalyst.
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The effects of gas exposure on the graphene/AlGaN/GaN heterostructure under UV irradiation
- Katarzyna Drozdowska
- Sergey Rumyantsev
- Janusz Smulko
- Andrzej Kwiatkowski
- Pavlo Sai
- Paweł Prystawko
- Aleksandra Krajewska
- Grzegorz Cywiński
This work demonstrates a graphene/AlGaN/GaN sensing device with two-dimensional electron gas (2DEG) toward nitrogen dioxide (NO2), tetrahydrofuran, and acetone detection under UV light irradiation. We propose combining measurements of the DC characteristics with a fluctuation-enhanced sensing method to provide insight into the gas detection mechanisms in the synergistic structure of highly stable GaN and gas-sensitive graphene. Both DC and low-frequency noise studies reveal the impact of UV irradiation (275 nm) on the GaN-based field-effect transistor (FET). Gas detection improves under UV light with higher differentiability between selected concentrations of inorganic (NO2) gas and the possibility of discrimination between weakly adsorbing organic species (tetrahydrofuran and acetone). Time-domain experiments confirm the stability and reversibility of sensor (short-time and long-time) responses and reduced time drift after employing UV light. Features observed in the 1/f noise spectra may indicate the high impact of the irradiation on the trapping states in the GaN-based heterostructure, which further modulates the fluctuations of the channel carriers in our device. Our findings broaden the view on AlGaN/GaN heterostructures modulated with a graphene gate for gas sensing purposes, including strongly binding inorganic gas and weakly adsorbing organic species.
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The effects of the IM1-12Br ionic liquid and the oxytetracycline mixture on selected marine and brackish microorganisms
- Lilianna Sharma
- Błażej Kudłak
- Grzegorz Siedlewicz
- Ksenia Pazdro
The number of applications and commercialized processes utilizing ionic liquids has been increasing, and it is anticipated that this trend will persist and even intensify in the future. Ionic liquids possess desirable characteristics, such as low vapor pressure, good water solubility, amphiphilicity, and stability. Nevertheless, these properties can influence their environmental behavior, resulting in resistance to biotic and abiotic degradation and subsequent water contamination with more harmful derivatives. However, there is a notable scarcity of data regarding the impact of mixtures comprising ionic liquids and other micropollutants. Identifying potential potentiation of ionic liquids (Ils) toxicity in the presence of other xenobiotics is a proactive risk assessment measure. Therefore, the study aims to fill an important knowledge gap and identify possible interactions between imidazolium-based ionic liquid (IM1–12Br) and the common antibiotic oxytetracycline (OXTC). During 11-day experiments, selected marine, brackish and freshwater microorganisms (diatom Phaeodactylum tricornutum, cyanobacterium Microcystis aeruginosa and green algae Chlorella vulgaris) were exposed to binary mixtures of target substances. The assessed responses encompassed chlorophyll a kinetic parameters related to photosynthesis efficiency, as well as pigment concentrations, specifically phycobilin content. Additionally, the impact on the luminescent marine bacterium Aliivibrio fischeri has been evaluated. Significant effects on the growth, photosynthetic processes, and pigment content were observed in all the targeted microorganisms. The concentration addition (CA) and independent action (IA) mathematical models followed by the Model Deviation Ratio (MDR) evaluation enabled the identification of mainly synergistic interactions in the studied mixtures.
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The elasto-plastic numerical study of crack initiation in notched PMMA specimens under uniaxial loading conditions – Tension and torsion
- Elżbieta Bura
- Andrzej Seweryn
This paper presents the results of FEM numerical calculations aimed at describing the plastic strain and stress fields under critical loading conditions: tensile force or torsional moment. The calculations were carried out with reference to the results of experimental tensile and torsional tests of flat PMMA specimens weakened with V-notches of different root radii: 0.5, 2 and 10 mm. The procedure for conducting nonlinear numerical analyses is described, including the determination of the actual hardening curve by the hybrid method. A high level of consistency between the results of the experimental and numerical calculations was obtained through description of PMMA with the elastic-plastic material model. The points of occurrence of stress maxima and plastic strain were indicated, which were taken as potential crack initiation sites. On the basis of the stress and plastic strain values measured at the critical points, a stress-strain fracture criterion was formulated, which was then positively verified.
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The Employment of Ukrainians as an Opportunity to Fill the Labour Market in Poland – Selected Issues
- Krystyna Gomółka
- Małgorzata Gawrycka
- Marta Kuc-Czarnecka
The labour market in Poland has undergone signifi cant transformations over the past two decades. The observed changes have been infl uenced by various factors related to, among other things, the possibility of free movement of the population resulting from membership of EU structures, demographic changes, technological changes, and the automation and robotisation of production processes. Demographic change is becoming a signifi cant challenge, highlighting the shortage of workers with different qualifi cations and competencies in the labour market in various sectors of the national economy. This paper aims to indicate to what extent Ukrainian citizens can fi ll the gaps in Poland’s emerging labour market. To that end, a survey was conducted in the Qualtrics programme in MayJune 2022 among Ukrainian citizens who arrived in Poland before 24th February 2022, i.e., before the outbreak of the war and who were registered in the Gremi Personal database. This particular company provides support connected to employment for Ukrainians. Due to the non-probabilistic sampling technique, the results cannot be generalised with regard to the entire population. To analyse the results, descriptive statistics were used to examine the population structure and determine the signifi cance of the characteristics studied and the correlation between them. The research shows that labour shortages in Poland’s labour market can be compensated to some extent by employing migrants from, for example, Ukraine. The commencement of the proper research was preceded by the preparation of a pilot study and the collection and analysis of statistical data related to the situation on the Polish labour market, taking into account the level and structure of employment and an indication of shortages in the labour market when the research was prepared, and the fact that complete statistical data ended in 2020, hence the decision to include this research period in the analyses.
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The energy concept of money
- Oleksandr Melnychenko
Purpose: This paper aims to provide the literature review seeking an answer whether energy can be used as a universal equivalent instead of money. Methodology: The author conducted a review of available literature and data sources related to the money theory and energy concept of money. Findings: It was found that the definition of energy as a general equivalent has a contextual and dynamic nature, and this field’s consolidation and logical expansion require a conceptual review. In this study, we talk about the basic principles of the energy concept of money: origin, recognition, and circulation. Throughout this paper, we explore key aspects of this new agenda, demonstrating that energy is at the heart of money circulation. Research limitations: It is suggested three areas for future research: quantifying the stability of energy price in the context of fiat money in dynamics, technological implementation of transactions, and the development of accounting technologies. Practical implications: Consolidating the available literature and providing suggestions on how money theory can be developed in light of the current energy challenges. The author’s approach the energy concept of money from an interdisciplinary perspective, including knowledge of economics, business, accounting, payment systems, law, and philosophy, to reflect on their own experiences. The energy concept of money in this study refers to the use of energy in a broad sense as a universal equivalent, the role of which is played today by money. Originality: In this paper, the author seeks to contribute to a deeper understanding of the energy basis of money by exploring the conceptual and empirical relationship between money, trust, and energy.
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The environmental dimension of city dwellers’ quality of life and the city’s social and spatial variability
- Maciej Brosz
- Małgorzata Dymnicka
- Iwona Sagan
- Jarosław Załęcki
The purpose of this paper is to attempt an analysis of the environmental dimension of the quality of life using quantitative surveys conducted among residents of Gdańsk. In the paper, we make reference to the theoretical assumptions ensuing from the concept of a comprehensive and integrated approach to the development of the urban environment, whilst noting the profound impact humans bring to their evaluation of the environmental components. The paper focuses primarily on the inhabitants’ attitudes to the environmental values of their place of residence in relation to things such as the condition and accessibility of green areas, air quality, potable water quality and noise intensity. The surveys indicate that views on the city’s environmental values are determined by numerous factors, such as the city’s territorial structure (districts) and its demographic structure (sex, age), and psychosocial features, such as a subjective sense of mental well-being.
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THE ESSENCE OF THE TRANSFORMATION OF SOCIO-ECONOMIC RELATIONS IN THE NATIONAL ECONOMY: THEORETICAL AND METHODOLOGICAL ASPECT
- Piotr Buła
- Oleksandr Melnychenko
The article is devoted to a thorough study of the theoretical and methodological foundations of the essence of the transformation of socio-economic relations of the national economy. Based on the study of scientific sources, a proper definition of the concept of "transformation of socio-economic relations" was formed. It is proposed to consider transformational processes from the point of view of their direct or indirect impact on other sectors and the economy in general. The need to understand and perceive the essence of transformation from the point of view of the transformation of socio-economic relations as such is well-founded. The article formulates the author's approaches to identifying the types of transformation of socio-economic relations, it’s possible and confirmed forms of manifestation, basic characteristics and features. The author's understanding of the concept of transformation potential of socio-economic relations of the national economy and the transformation cycle is outlined. A vision of the intensity, efficiency and frequency of transformational changes and the limits of transformation was formed. Characterization of the period and stages of transformational changes that lead to socio-economic shocks and cause socio-economic instability, periods of fluctuations, including ups and downs, socio-economic crisis, transformational trap is made
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The evolution of education spaces - from plan as generator to regenerative architecture, virtual rooms and green campuses
- Jakub Szczepański
- Lucyna Nyka
The study programmes are often considered the main formative factors in the process of educating future architects. Another highly influential component is the architectural characteristics of learning spaces, and consequently the impact of the physical built environment on the quality of education has been widely discussed. However, not often do we realise that the characteristics of education spaces correlate with the organisational structure of schools of architecture. Thus, the purpose of this article is to identify the trends in the evolution of educational spaces for training future architects, and investigate how much their characteristics have always been dependent on the architectural theories of the time and correlated with the organisational structure of the schools of architecture. The conclusions allow to draw a postulate that not only spaces ought to be in a focus of prospective future transformations, but also re-thinking the organisational structure of the schools of architecture.
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The Finite Elements Method application to assesment the impact of turbulence generated by wind turbines on their lacation inclose proximity of overhead high voltage power transmissionlines
- Waldemar Kamrat
The paper presents selected aspects of construction of wind turbines location concerning aerodynamic impact on power lines. Reaserch is based on the source data concerning the aerodynamic impact of a wind farm consisting of 8 turbines and 400 kV power line, an analysis of the possibility of wind farm locating in the immediate vicinity of the line was carried out. There are serious problems with locating higher capacity wind farms in the context of their connection to the transmission grid. Reaserch facilitate the wind farm location in proximity of an overhead high-voltage power transmission line maintaining safety and efficiency.
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The fracture behaviour of notched PMMA specimens under simple loading conditions – Tension and torsion experimental tests
- Elżbieta Bura
- Andrzej Seweryn
This paper presents the results of experimental testing of flat PMMA specimens during uniaxial loading conditions. Two separate tests were conducted: tensile and torsion. The specimens were weakened with V-type edge notches with different root radii: 0.5; 2 and 10 mm. The specimens were made in two thickness variants: 5 and 15 mm. Monotonic tensile and torsion tests were carried out while keeping the averaged strain rate constant, due to the strong influence of this parameter on the PMMA behaviour. The procedure for non-contact measurement of the torsion angle using the ARAMIS 3D 4 M vision system is described. A set of PHANTOM cameras was used in the study, thanks to which all fracture processes were recorded. The processing of the obtained recordings made it possible to precisely indicate the moment (critical value of tensile force, torsional moment) and the location of crack initiation, as well as determine the nature of their evolution. Microscopic observations showed the structure of the failure surface and clearly indicated the different initiation sites observed for the two simple loading states. Different crack initiation angles were indicated, depending on the type of test conducted, as well as the notch root radius. The material in the article provides a starting point for numerical modelling of the fracture processes of notched elements and verifying the fracture criteria.
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The Idea of a Student Research Project as a Method of Preparing a Student for Professional and Scientific Work
- Krzysztof Nowicki
- Mariusz Kaczmarek
- Paweł Czarnul
In the paper we present the idea and implementation of a student research project course within the master’s program at the Faculty of Electronics, Telecommunications and Informatics, Gdansk Tech. It aims at preparing students for performing research and scientific tasks in future professional work. We outline the evolution from group projects into research project and the current deployment of both at bachelor’s and master’s levels respectively, management of projects i.e. steps, reporting and monitoring at both faculty and individual project’s levels within our custom-built Research Project System (RPS). We further elaborate on adopted formal settings and agreements especially considering the possibility of external clients taking part in the projects. Methodology of conducting and several examples of awarded projects are presented along with statistics on the number of submitted/conducted projects as well as those finalized with actual submitted/published research papers/patents proving actual (inter)national impact of the course.
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The Idea of Using Adhesive Bonds in Shaping of Cold-formed Thin-walled Beam-columns
- Marcin Kujawa
- Antonio Cazzani
- Łukasz Smakosz
- Violetta Konopińska-Zmysłowska
- Karol Winkelmann
- Faizullah Jan
- Czesław Szymczak
The chapter concerns the idea of using adhesive bonds in the shaping of cold-formed thin-walled beam-columns. The idea of adhesive-bonded connections is not new but is unlikely to have been used in the design and shaping of thin-walled beam-columns in civil engineering up to date. Metal bar structures, including (due to economic reasons) thin-walled structures, are the most common and effective means to build engineering superstructures/loadbearing structures. Over the years, classical techniques of connection between individual structural elements, such as bolting or welding, have mainly been used. However, the classical types of connections have their disadvantages, eliminable by using less conventional solutions, e.g. the adhesive-bonded connections. The use of structural adhesives in engineering, particularly in metal construction design, unfortunately still raises questions about their durability and load-bearing capacity. An important issue in the case of bonded structures is the effect of creep on the behavior of such joints. These issues undoubtedly require further research in the context of bonded joints. The topic still needs fundamental research of empirical and theoretical nature that will contribute to the acquisition of new knowledge on the mechanical phenomena occurring in adhesively bonded metal structures. The authors also expect that in the long run, the idea will be widely used in modern-day civil engineering.
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The Impact of Contemporary Technology on Shell Structures: Material and Light Solutions
- Jan Cudzik
- Aygün Atasoy
With the development of technology and the materials used, shell structures have developed into more complex forms. This article is a comparison between contemporary and historical shell structures. The change is an effect of the evolution in the design process that is the result of parametric design thinking. The study aims to investigate the impact of new technologies on the architectural form of shell structures. Was there any pivot point in the history of shell structures? The secondary objective of the study is the focus on lighting in such forms and their evolution with the view of the evolution of lighting solutions applied in architecture. With the use of new technologies, shell structures can have a new form and complex detail. They may vary in scale from small objects to large-scale structures.
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The impact of filler thermomechanical modifications on static and dynamic mechanical performance of flexible foamed polyurethane/ground tire rubber/zinc borate composites
- Aleksander Hejna
- Paulina Kosmela
- Adam Olszewski
- Krzysztof Formela
- Łukasz Zedler
- Adam Piasecki
- Katarzyna Skórczewska
The rapid development of the automotive industry is very beneficial to many aspects of human life, but it is also a very significant environmental burden. The most straightforward impact is related to the generation of exhaust, but the management of post-consumer car parts is also a major challenge. Among them, waste tires are very burdensome due to their enormous numbers. Therefore, it is essential to develop novel, environmentally friendly methods for their disposal, which would reduce their environmental impacts. One of the most promising approaches is shredding, resulting in the generation of ground tire rubber (GTR), which can be introduced into polymeric materials as a filler. The presented work is related to the thermomechanical treatment of GTR in a twin-screw extruder assisted by zinc borate (ZB), whose incorporation is aimed to increase interparticle friction within the extruder barrel. The impact of the treatment conditions on the particle size and surface development of the GTR/ZB compositions was evaluated. Modified GTR was introduced into flexible polyurethane (PU) foams, and the impact on the static and dynamic mechanical performance of the resulting composites was investigated. Increasing the treatment temperature occurred to have an adverse effect on the tensile performance of the composites due to the agglomeration of GTR particles limiting the efficiency of stress transfer, which was also confirmed by dynamic mechanical analysis. On the other hand, increasing the ZB share in the GTR/ZB compositions limited PU disruptions related to the reactivity of the GTR functional groups with isocyanates, which enhanced the mechanical performance of the composites. It was proven that the proposed method of GTR thermomechanical treatment assisted by ZB might benefit the performance of flexible PU foamed composites, which could broaden the application range of GTR and provide novel ways for its efficient utilization